1. Field of the Invention
The present invention relates to a power tester for testing reaction time and muscular power. More specifically, the present invention relates to a portable power tester which can be used to determine muscular power.
2. Description of Related Art
Rehabilitation specialists are often asked to conduct an assessment of patients that have acquired a limitation to their optimal independent activity. Although the parameters of human performance vary widely, one may identify several principles which are common to all forms of independent activity. Such common principles are muscular strength, endurance, joint range of motion, and motor coordination. It is these parameters of performance that the rehabilitation specialist focuses upon. The specialist directs attention to identified parameter""s which are limiting performance and evaluates the degree of the limitation.
Historically, the rehabilitation specialist has a hands on approach using his own healthy limb to resist the movement of the patient""s limb. In this way, the clinician evaluates the patient""s performance through feel and, at the same time, offers exercise to the limited muscle group. By repetitive hands on accommodating exercise, the limited muscle group is overloaded and adapts biologically with improved performance.
Muscle strength is a performance parameter which is quite plastic and quickly adapts to immobilization or disuse as well as to increased activity or overuse. That is, muscle strength quite quickly increases or decreases with respect to use or disuse. Disuse, such as immobilization following injury or casting after surgery, results in a significant decrease in muscle size and muscle strength. In contrast, if free weight lifting is used as the method of choice for the rehabilitation therapy, the end result is a quick response of increased muscle cell size and gain in muscle strength.
Weight lifting equipment overloads a muscle group by using gravity against which a muscle must move the weight. With free weights, no controls are present to direct the speed of movement of the limb nor the resistance throughout the range of motion that the muscle must work against. The maximum free weight resistive load that can be applied to a limb is determined by the capacity of the associated muscle group as measured throughout the range of motion of the limb. The maximum load that the limb can support varies throughout its range of motion where at some point it is at a minimum and at another it is at a maximum. Hence, the maximum resistive free weight load that can be applied is equal to the maximum supportable load in the weakest area of the range of motion.
Conventional methods of subjective assessment and reconditioning, such as subjective xe2x80x9cthrough the clinician""s handsxe2x80x9d evaluations and free weight exercise, are now reinforced with technology.
Technology has been developed which provides for assessment and reconditioning of muscular deficiencies by electronic control of the rate of movement of the limb. The rate of movement control is achieved by constantly varying the amount of resistance offered the moving limb throughout the range of motion. This category of devices allow the muscle group, usually a whole limb or limb segment, to accelerate to a pre-selected speed. These constant speed devices use the methods of isokinetic or accommodating resistance.
Isometric assessment of muscular strength has been employed extensively in orthopedic, sports, rehabilitation, and industrial clinics for more than 40 years. Isometric testing typically involves a maximum voluntary contraction at a specified joint angle or functional position against an unyielding pad or handle connected to a force measuring device. In contrast to isometric testing, isokinetic testing measures strength throughout a range of motion of a body segment using a yielding, constant velocity device to which a force measuring device is attached. The isometric testing modality has become more popular due to the availability of testing products.
The first generation of isometric testing devices was developed in the early 1980s and involved measurement of only the maximal force using a cable tension meter or dial gauge. The disadvantages of these systems include the ability to measure only gross large forces, poor sensitivity at small forces, and an inability to dynamically measure forces. Additionally, the cable systems were cumbersome, setup times were long, and the number of muscle groups that could be tested was severely limited.
The second generation of these isometric testing devices used computerized testing platforms with a chair utilized for upper and lower extremity bilateral testing, spine evaluations, and lifting assessments. These systems analyzed the force curve over time, provided feedback on cogwheeling, measured fatigue, determined rate of contraction, assessed consistency of effort, calculated averages, determined bilateral deficit, etc., all related to the performance of a patient.
One disadvantage of the above-described devices is the non-integrated test chair. The chairs included in these devices were added as an afterthought. The chairs used considerable floor space due to their size, were heavy, and were wheeled or carried into place over the platform for use. In addition, the patient was removed from the chair and the chair moved several times during most exams, making the exam longer and more involved.
Another disadvantage of the above described devices is that the load cell operates in tension only, requiring multiple setups for antagonist/agonist testing. In order to provide assessments of antagonist/agonist muscle groups, cumbersome cables or straps must be used. After testing the agonists, the patient and chair must be turned around to keep the load cell in tension to test the antagonists, which increases the setup and documentation time considerably. For example, when measuring the biceps, the handle, cable, and transducer are pulled to place them in tension. When measuring the opposite motion (elbow extension using the triceps), however, the patient and chair are turned around to keep the cable/strap in tension. This requires two different setups for the chair and patient. In addition, moving in and out of the chair for every test may prove even more time consuming, burdensome, and painful for injured patients.
A further disadvantage with these above described devices is that they use two-dimensional positioning to orient the load cell with respect to the muscle group being tested, requiring complex bilateral testing setups. The positioning methods of most systems include adjustment of the load cell height, load cell angle in the vertical plane, horizontal distance from the load cell acting point, chair orientation, etc. But in most systems, the direct line of action between the plane of movement of the muscles being tested and the centerline of the transducer results in large errors in maximal force. For example, during a knee flexion test, the patient is seated in a chair and a strap is connected around the leg just above the ankle. The tranducer is lowered so the strap is horizontal. When the patient is seated in front of the transducer, the line of action is 24 degrees resulting in a strength measurement error of approximately 10 percent.
In view of the above disadvantages, there is a need for a device which provides for more convenient and accurate bilateral testing. In order to solve this problem, some devices move chair and the patient, to the right for left side testing and to the left for right side testing. This cumbersome procedure equalizes the line of action for the muscles being tested and the tranducer, but the patient is required to exit the chair, the chair is moved, and the patient is then repositioned on the chair. If multiple tests are required, the problem is compounded. Thus, there is a need for a more convenient device for bilateral testing. In addition, there is a need for a device that provides a direct line of action between the transducer and the point line of action.
Prior art devices have decreased repeatability of the tests due to the use of cables and straps. The use of cables and straps makes it difficult to position the patient exactly the same for follow-up tests. There is a need for a device that eliminates straps and cables to improve the repeatability of follow-up tests.
The above described prior art devices are unable to meet clinical requirements for functional diagnostic testing or post offer employee testing. Functional diagnostic testing in clinical environments requires a device that may be quickly customized for testing. Post-offer employee testing requires objective, baseline, tester independent, easy to administer, standard, and job specific isometric strength tests. Current devices were not designed for these emerging uses. There is still a need for a device that can be quickly customized for different tests and provide objective and easily administered tests.
In the isokinetic system, once the moving limb achieves the selected speed, the device then offers the muscle group an accommodating resistance which is proportional to the contractile force such that the limb continues to move at the selected speed. These mechanisms usually have some form of position/time feed back, servo loop which directs the resistance, for example, through feeding a variable current to a DC servo motor, such that, no matter what constantly varying force is executed by the contracting muscle group, the limb does not exceed or fall below the speed selected.
The goal with isokinetic systems is that throughout the entire range of motion of the limb, the associated muscle groups are working at their utmost level while receiving an optimal overloading resistance.
The contractile effort of a muscle group against this type of microprocessor based resistance is registered by the system and produces a profile of contractile performance which is widely recognized as accurate and repeatable. The data from such a system can be used in a court of law as evidence in disability claims.
Examples of such isokinetic systems are the Cybex, manufactured by Lumex, U.S. Pat. No. 3,465,592, inventor J. Perrine; the LIDO manufactured by U.S. Pat. No. 4,601,468; inventor M. Bond, KIN COM manufactured by Chattanooga, U.S. Pat. No. 4,711,450, inventor J. McArther; the Biodex, U.S. Pat. No. 4,628,910, inventor R. Krukowski and U.S. Pat. No. 4,691,694, inventor R. Boyd, et al.; and the devices disclosed in U.S. Pat. Nos. 3,848,467 and 4,235,437. Each of these systems use the method of isokinetic resistive exercise/assessment applied to the large muscle groups of the legs particularly the knee.
Attachments are also available to modify these devices to address the arms and, secondarily, the ankles, wrists, and hands. With respect to the hands, gross movements are allowed by these systems which include an attachment which simulates the grip motion one would use with pliers and an attachment which has a moving rod element, with the firearm rigidly fixed, for simulation of certain wrist activities. In each case, a specific work task is simulated with these accessories.
The shortcoming of these devices is that the movements described by the hand are those which are seen specifically at job sites or only rarely in life. Reliability of the assessment data is questionable with these systems due to the inability to accurately reproduce the same posture and set up for each trial. These devices are best suited to exercise muscle groups and areas of muscle groups. The assessment aspect of these devices is severely limited by the design.
Other devices have been developed with similar intentional designs limiting the use of the system to simulations of specific work tasks. For example, U.S. Pat. Nos. 4,337,050 and 4,768,783 issued to Engalitcheff, Jr. disclose a method and apparatus for rehabilitating injured muscles. The Engalitcheff, Jr. patent discloses an apparatus which includes a number of specific accessory elements simulating various tools coupled to a controlled resistance device. These accessories allow the therapy to address the particular work tasks an individual may be expected to perform. Each accessory element is specifically adapted to the resistance device, which includes a rotatable shaft, controlled, in one embodiment, by an electric brake coupled to an adjustable voltage source. Ostensibly, selective resistance is provided to each of the variety of various accessories to permit exercise of specific muscles or joints in simulated industrial applications. Feedback regarding the amount of force applied to each particular exercise is provided by a voltmeter; no other type of data feedback is provided.
A more sophisticated rehabilitation system, which also includes means for evaluating muscle degradation, is the LIDO.RTM. WorkSET that is manufactured by Loredan Biomedical, Inc., Davis, Calif. The Loredan device includes an adjustable resistance head, to which a number of accessories may be coupled, and various other tool-type accessories for simulating work-related activities. The resistance head generally includes a gear reducing element and a D.C. servo motor, appropriately sized to provide resistance for the various tool accessories. A personal computer controls the resistance applied to all accessories of the system, providing variable resistance to each of the accessories attached thereto for a series of exercise and evaluation modes. The Loredan system is capable of automatically implementing three general types of exercise for a test subject: isokinetic; isotonic; and isometric exercise. The isokinetic exercise mode generally provides a variable force against the particular motion undertaken by the subject, with the exercise accessory, to maintain a constant velocity on the test subject""s action. The isotonic exercise mode provides a constant force against the test subject""s actions to allow the subject to move the accessory device at varying speeds. The isometric exercise mode deals generally with the static measurement of the flexing and extension of particular muscles, including both concentric and eccentric contractions.
The Loredan system requires a physical floor space area of approximately 8xe2x80x2 by 8xe2x80x2, generally making it suitable only for large scale rehabilitative efforts. The numerous attachments are adaptable to allow rehabilitation of many muscle groups in a manner similar to the of the Engalitcheff, Jr. patent devices.
It would be useful to provide a system for the comprehensive evaluation of muscles of the body.
According to the present invention, there is provided a method of testing power in an individual by measuring the amount of time it takes the individual to move an object from one location to a second location and automatically calculating the power based on the time it took to move to object. Also provided is a power tester including a sensor device for sensing movement of a weight between at least two points, measuring device for measuring time for weight to move between at least two points, and a calculating device for automatically calculating power based upon the measurements.